If you have a Tesco(larger stores) beside you, they have value pillow stuffing. It's only 2e for a decent size bag. That is what I use and I only just got a second bag, 2yrs on. I have used it in my canister, HOB's and internals. I NEVER rinse it and reuse it, so that shows you how far it goes. I just dump it when it's time to change it. It is completely fish safe, no additives.
The stuff from the LFS's is a lot more expensive, if you can find it!!!